The present invention relates in general to top feeders for sewing machines and in particular to a simplified arrangement linking a top feeder to the primary sewing machine drive.
For many years, sewing machines have been provided with a lower feed mechanism, usually located formed through an opening in the work surface of the machine adjacent the stroke of the sewing machine needle and operating to engage the undersurface of materials being sewn and periodically to advance the material to, and past, the needle. Because such a feeding arrangement acts positively only on the lowermost surface of the plural layers of material being sewn, it has long been desired to provide in a sewing machine an arrangement which would achieve a positive feed of the upper layer of material in addition to the conventional positive feed of the lower layer of material. Such an arrangement was recognized as being badly needed in so-called overedgers and safety-stitch sewing machines.
Various approaches have been attempted, such as rotary feed wheels driven through flexible cables and bearing upon the top surface of materials being sewn. Yet, success was minimal until the introduction of a "top feeder" that operated in synchronism with the conventional lower work feeder to provide for a positive feeding of the entire "sandwich" of material being sewn. This previous "top feeder" is the subject of U.S. Pat. No. 3,530,809, issued Sept. 29, 1970 to Robert E. Porter, the disclosure of which is incorporated herein by reference.
While the feeding arrangement described and claimed in U.S. Pat. No. 3,530,809 has enjoyed substantial success, it has become apparent that various improvements over the feeding arrangement shown in that patent can yield substantially improved performance: e.g., less wear, smoother and quieter operation, simplicity of repair and interchange of parts, more positive gripping of the material being sewn, etc. Two such improvements are disclosed in U.S. Pat. No. 3,995,571 issued Dec. 7, 1976 and U.S. Pat. No. 4,166,422 issued Sept. 4, 1979 to Robert E. Porter, the disclosure of both of these patents also being incorporated herein by reference.
In most of the improved top feed arrangements, there has been an accumulation of linkage and other mechanism which can interfere with ease of operation and reduce available working area.
Accordingly, the primary object of the present invention is a top feed arrangement for a sewing machine which not only has improved performance in one or more of the areas mentioned above but which also is of vastly simplified design and provides a large uncluttered work area.